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taith taire gatnt @Hirn HENRY F. ROBERTS,V F FAYET'IE- CITY, PENNSYLVANIA.

Letters Pam No. 65,437, daad me 4, 1867.

IMPROVEMENT III STEAM ENGINES.

dhp Satana rrrrm tu in ilpsr Enters gnent mit mating part ai te same.

'IO ALL WHOM IT M AY GONCERN:

Be it known that I, HENRY F. ROBERTS, of Fayette City, in the county of Fayette, and State of Pennsylvania, have invented a new and useful Improvement in Steam Engines; and I do her'eby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing, in which- Figure 1 is a top view of the two cylinders employed for the purposes of my improvement.

Figure 2 is a vertical longitudinal section of thelarger cylinder' shown in fig. 1.

Like letters of reference in each of the figures denote similar parts of the apparatus.

Low-pressure engines as ordinarily constructed exhaust the waste steam into a vessel in which it is con densed, thereby forming a vacuum which relieves the escape steam of the resistance of the atmospheric pressure, but by this means all the power of the exhaust steam is wasted, excepting that which is represented by the heat ofthe water of condensation. In high-pressure engines, on the other hand, the exhaust steam is allowed to escape directly into the external air, and in addition to' the direct loss of power thus produced, there is a furtherl loss consequent on the resistance of the atmospheric pressure on thc column of escaping steam, which is even greater than the weight ofthe atmospheric pressure on a surface equal to the area of the escape-valves, owing to the va thicrtz' of the air when struck by a column of steam moving with great velocity, consequently the available working power of such engines is only equal to the difference between the pressure of live steam on the piston and the resistance of the atmosphere to the escaping steam. By my 'invention I propose to prevent this lossof power in high-pressure engines, and at the same time utiliae a great part of the power ordinarily wasted by the condensation of steam in low-pressure engines; and in such process, and the apparatus which I have invented for its practical application, consists the nature of my invention.

To enable others skilled in the art to use my invention, I will proceed to explain the construction and operation of my apparatus.

In the drawings, is the cylinder such as is ordinarily used in Ahigh-pressure engines, furnished with a piston attached to the piston-rod B. C is the steam-chest, con-taining the valves for the admission of live steam into the cylinder, operated by the valve-rod a. E E are cases,vone at each end of the working cylinder A, and each containing a valve for the' passage of exhaust steam from the cylinder, which valves are connected by the rod e and operated through the arm c hy the engine, lto exhaust the steam at the proper time from either end of thc cylinder. From the exhaust-valve case E a pipc,f, and from the exhaust-valve case E a pipe, f', conduct the escape steam into the opposite ends of' the low-pressure cylinder D, the length and diameter of which are greater than the lengthanrl diameter' of the high-pressure cylinder A, heilig of such relative proportion that steam worked in cylinder A at one hundred pounds pressure shall, when exhausted into the larger cylinder D, be expanded so as to be only a little over one atmosphere, or about seventeen pounds pressure. The pipcsf and j" which conduct the exhaust steam from the cylinder' A into the larger cylinder D, may pass immediately from one cylinder to thc ot/hcr, or, shown in iig. 1,) may be lengthened by means of elbows so as to give greater' condensing surface. The cylinder'D, if necessary, may be enveloped with water by means of an outer casing, the water being allowed to flow through the casing around the cylinder, seas to expedite the condensation of steam therein. lThe exl1aust-valves E and E of tlie.cyliuder A. serve as iulet-valve; for the cylinder D. The cylinder D is furnished with a piston, g, and piston-rod, h, which is connected in the usual manner to the same machine as the piston-rod D of the cylinder A., so that they shall co-operate to produce the desired motion of the engine. The purpose of this combination of two working cylinders is to use the expansive force of the live steam in the cylinder A, and then, instead of escaping the exhaust steam into the open air, to pass it into the cylinder D, which is of so much greater capacity that the steam will expand freely and without resistance, and when so expanded, to condense it rapidly, so as to produce'avacuum (more 0r less perfect) inthe larger cylinder, and thus worl; the piston of the larger cylinder by means of the escape steam at one end of the cylinder and a vacuum at the other end. /llo ciect the necessary condensation of steam in the larger cylinder D, (in addition to the water-jacket, if that hc t'ound nccessary,) I introduce a jet of cold water into that end of the cylinder which has heen filled with steam by means of the pipe k, which extends from one end of the cylinder D to the other, and opens into it at cach extremity. The pipe c is furnished with two cocks or valves, Z l", which must he connected with the engine, as to open and close alternately, and at the proper times. ',ihe water of condensation which forms in the cylinder D, with the water introduced by the pipo 7c, is drawn off through the pipe m, (sce fig. 2,) from both ends ofthe cylinder, this pipe m being furnished with cocks or valves, n n', operated by th'e engine alternately, and at the proper times. As this water of condensation is nearly as hot as boiling water, I pump it from the'pipe mV by a small pump worked by the engine, or by the doetor, into the steam boiler, and thus economize heat, and avoid the Waste of fresh water which is so important in ocean Steamers.

The operation of my engine is as follows: The live steam having been worked (at a pressure sayof one hundred pounds) in the high-pressure cylinder A, escapes through the valves E E', and instead of meeting with the resistance ofatmos'pherie pressure, is aided in its passage out by the operation of thelarge cylinder D, which acts as a pmp'to draw it into it. Passing into one end ofthe loW-pressure cylinder D, it expands freely as the piston recedes until'it has .little more force than the pressure of the atmosphere, say seventeen pounds. It is then condensed by the injection of cold wut-er through the pipe 7c, creating a vacuum, more or less complete, when the piston moves towards that end of the cylinder, while at the same moment the exhaust Steam from the cylinder A enters the cylinder D at the other end. Thus the two engines work together, either in the same or opposite directions, according to the direction which the exhaust steam takes in passing from one cylinder to the other. l

The advantages of my improvement may be briefly stated as follows: By combining a high-pressure cylnider with a low-pressure cylinder I secure the advantages of both kinds of engine and obviate the defects of both in a great degree. I .escape the loss of heat and of power consequent upon the exhausting of the worked steam into the openair in a high-pressure engine, and utilize the power lost in the condenser of a low-pressure engine;

and in addition to vthese advantages I nearly double the working capacity ofthe engine by using the steam twice over, first employing its active force, and then by means of condensation securingl the aid of a vacuum on one side of the piston, the other side of which is acted upon by the escape steam frolnthe high-pressure cylinder. This increase of power is in e'eet a saving of fuel, as less steam is required t0 do the same amount of' work. I also obviate the necessity of using steam of very high pressure, and thereby lessen the danger of explosions.

Having thus described my improvement in steam engines, what I claim as my invention, and desire to secure by Letters Patent, is Y The large steam cylinder D, furnished with a piston and piston-rod, and with the pipes t and m, for admit. ting and discharging water alternately at its opposite ends, in combination with a higlrpressure steam cylinder, A, when such cylinders are connected together by exhaust steam pipes ff', substantially as and for the purposes hereinhefore described.

Intestimony whereof I, the said HENRY F. ROBERTS, have hereunto set my hand in presence of` H. F. ROBERTS. Witnesses GEORGE H. CnnIsTY, A. S. NICHOLSON. 

